insidious

adjective

Definition of insidiousnext
as in treacherous
formal causing harm in a way that is gradual or not easily noticed Most people with this insidious disease have no idea that they are infected. an insidious enemy

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Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Recent Examples of insidious Meanwhile, an insidious supervillain (Kenneth Branagh) lurks, threatening to take Crown down. — Mya Copeland, Variety, 29 July 2026 But there’s a historical, and some might argue insidious, irony to all of this. — Drew Pittock, USA Today, 25 July 2026 But, as Ellis demonstrates in this survey of the city’s racial history, liberal policy achievements tend to obscure more insidious forms of exclusion. — The New Yorker, New Yorker, 20 July 2026 Beneath all the splendor, the couture, the balls, and the opera lurked an undercurrent of hatred, one that would fester and erupt in ways both insidious and catastrophic. — Literary Hub, 17 July 2026 See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
  1. treacherous
  2. subtle
  3. false
  4. deceptive
  5. perfidious
  6. incorrect
  7. wrong
Adjective
  • When planning paths and features, follow the contour of the slope rather than going straight up and down to slow water and create less treacherous access.
    — Mary Marlowe Leverette, Southern Living, 11 Aug. 2026
  • The Hand of the Queen will have a treacherous road ahead, especially with the increasingly dictatorial Queen Rhaenyra (Emma D'Arcy), who was in no big rush to save Corlys from Ormund's clutches.
    — Bryan Alexander, USA Today, 10 Aug. 2026
Definition of treacherous
Adjective
  • Clinicians found real value in cases involving subtle fractures in the knees, feet and other extremities, where conventional X-ray findings were inconclusive or missed the fracture altogether.
    — Erez Meltzer, Forbes.com, 21 Aug. 2026
  • Then there are the subtle vanilla notes like those found in Orb Oils’s Lenny fragrance, matcha in Le Labo’s, or, say, Flamingo Estate’s Prinsesstårta roll-on captures notes of marzipan like a slice of Sant Ambroeus Princess cake.
    — Arden Fanning Andrews, Vogue, 21 Aug. 2026
Definition of subtle
Adjective
  • But to build a web of accusations based on false premises and the manipulation of reality in order to attack the Biennale and a film invited to compete is a petty and unacceptable act.
    — John Bleasdale, Variety, 19 Aug. 2026
  • China’s aircraft engineers have warned that artificial intelligence could feed false data into military intelligence, potentially distorting the design and operation of advanced weapons.
    — Aamir Khollam, Interesting Engineering, 19 Aug. 2026
Definition of false
Adjective
  • The company alleges trademark infringement, unfair competition and deceptive trade practices.
    — Jason St. Angelo, USA Today, 19 Aug. 2026
  • And, given his high release point, deceptive delivery and deep repertoire, where batters can’t often make good contact.
    — Marc Topkin, The Orlando Sentinel, 19 Aug. 2026
Definition of deceptive
Adjective
  • Logan Marshall-Green as Melanthius Melanthius is a perfidious goatherd who sides with Antinous.
    — Hannah Abraham, Forbes.com, 18 July 2026
  • This is perhaps the most perfidious practice of this sort of politics.
    — David M. Drucker, Twin Cities, 3 June 2026
Definition of perfidious
Adjective
  • When requirements are unclear, AI may make incorrect assumptions that compound over multiple iterations.
    — Son Nguyen, Forbes.com, 18 Aug. 2026
  • The senators also noted that grants were canceled out of the blue with form letters, which had contradictory explanations and incorrect citations.
    — Beth Mole, ArsTechnica, 18 Aug. 2026
Definition of incorrect
Adjective
  • The company’s investment in the hedge fund, as well as wrong-way bets in Asian equity markets, drove part of the losses, said the person, who asked not to be identified citing private details.
    — Katherine Doherty, Fortune, 15 Aug. 2026
  • Maybe in this new era, more things will go right than wrong for the Mets.
    — Abbey Mastracco, New York Daily News, 15 Aug. 2026
Definition of wrong

Browse Nearby Words

inside tracks
insidious
insidiously
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Cite this Entry

“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 22 Aug. 2026.

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Nglish: Translation of insidious for Spanish Speakers

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